Endothelial dysfunction in young patients with acute ST-elevation myocardial infarction

Low physical activity is associated with impaired endothelial function in patients with type 2 diabetes and controls after 5 years of follow-up

BACKGROUND

The long-term association between physical activity and endothelial function has not previously been investigated in patients with type 2 diabetes. Therefore, we aimed to evaluate the relationship between physical activity and endothelial function, assessed by peripheral arterial tonometry, in patients with type 2 diabetes and non-diabetic controls after 5 years of follow-up.

METHODS

We included 51 patients with newly diagnosed type 2 diabetes and 53 sex- and age matched controls. Participants underwent baseline clinical characterization including objective measurement of physical activity level using accelerometery. After 5 years of follow-up, participants were re-examined, and endothelial function was assessed as natural logarithm of reactive hyperemia index (lnRHI).

RESULTS

Physical activity at baseline was associated with lnRHI after 5 years of follow-up in both patients with type 2 diabetes and controls. An increase of 1 standard deviation (SD) in daytime physical activity corresponded to a 6.7 % increase in RHI (95 % confidence interval: 1.1;12.5 %, p = 0.02). We found no difference in lnRHI between patients with diabetes and controls (0.67 ± 0.29 vs. 0.73 ± 0.31, p = 0.28).

CONCLUSIONS

Daytime physical activity is associated with endothelial function after 5 years of follow-up in patients with type 2 diabetes and controls.

Higher levels of daily physical activity are associated with better skin microvascular function in type 2 diabetes-The Maastricht Study

Objective

Physical activity may provide a means for the prevention of cardiovascular disease via improving microvascular function. Therefore, this study investigated whether physical activity is associated with skin and retinal microvascular function.

Methods

In The Maastricht Study, a population‐based cohort study enriched with type 2 diabetes (n = 1298, 47.3% women, aged 60.2 ± 8.1 years, 29.5% type 2 diabetes), we studied whether accelerometer‐assessed physical activity and sedentary time associate with skin and retinal microvascular function. Associations were studied by linear regression and adjusted for major cardiovascular risk factors. In addition, we investigated whether associations were stronger in type 2 diabetes.

Results

In individuals with type 2 diabetes, total physical activity and higher‐intensity physical activity were independently associated with greater heat‐induced skin hyperemia (regression coefficients per hour), respectively, 10 (95% CI: 1; 18) and 36 perfusion units (14; 58). In individuals without type 2 diabetes, total physical activity and higher‐intensity physical activity were not associated with heat‐induced skin hyperemia. No associations with retinal arteriolar %‐dilation were identified.

Conclusion

Higher levels of total and higher‐intensity physical activity were associated with greater skin microvascular vasodilation in individuals with, but not in those without, type 2 diabetes.

Differentially Expressed Proteins in Primary Endothelial Cells Derived From Patients With Acute Myocardial Infarction

Endothelial dysfunction is one of the primary factors in the onset and progression of atherothrombosis resulting in acute myocardial infarction (AMI). However, the pathological and cellular mechanisms of endothelial dysfunction in AMI have not been systematically studied. Protein expression profiling in combination with a protein network analysis was used by the mass spectrometry-based label-free quantification approach. This identified and quantified 2246 proteins, of which 335 were differentially regulated in coronary arterial endothelial cells from patients with AMI compared with controls. The differentially regulated protein profiles reveal the alteration of (1) metabolism of RNA, (2) platelet activation, signaling, and aggregation, (3) neutrophil degranulation, (4) metabolism of amino acids and derivatives, (5) cellular responses to stress, and (6) response to elevated platelet cytosolic Ca²⁺ pathways. Increased production of oxidants and decreased production of antioxidant biomarkers as well as downregulation of proteins with antioxidant properties suggests a role for oxidative stress in mediating endothelial dysfunction during AMI. In conclusion, this is the first quantitative proteomics study to evaluate the cellular mechanisms of endothelial dysfunction in patients with AMI. A better understanding of the endothelial proteome and pathophysiology of AMI may lead to the identification of new drug targets.

Intensive treatment of hyperglycemia in the acute phase of myocardial infarction: the tenuous balance between effectiveness and safety - a systematic review and meta-analysis of randomized clinical trials

INTRODUCTION

In acute myocardial infarction (AMI), each 18 mg/dl (1 mmol/L) increment is associated with a 3% increase in mortality rates. All strategies applied for reducing blood glucose to this date, however, have not presented encouraging results.

METHODOLOGY

We searched the Medline (PubMed) and Cochrane Library databases for randomized clinical trials (RCTs) from 1995 to 2017 that used the intensive strategy or GIK therapy for blood glucose control during the acute stage of the AMI. We included eight studies. In order to identify the effects of GIK or insulin therapy, we calculated a overall risk ratio (RR) with meta-analysis of fixed and random effects models. A two-tail p-value of < 0.05 was considered statistically significant.

RESULTS

A total of 28,151 patients were included: 1,379 intensively treated with insulin, 13,031 in GIK group, and 13,741 in the control group. The total mortality was 10.5% (n=2,961) and the RR of 1.03 [95%CI 0.96-1.10]; I2 = 31%; p = 0.41 for the combined intensive insulin plus GIK groups in comparison with the control group. In meta-regression analyses, intense reductions in blood glucose (> 36 mg/dL) in relation to the estimated average blood glucose (estimated by HbA1c) were associated with higher mortality, whereas lower reductions in blood glucose (< 36 mg/dL) were not associated with mortality. The lowering of blood glucose in the acute phase of MI compared with the average blood glucose was more effective around 18 mg/dL.

CONCLUSION

This meta-analysis suggests that there may be a tenuous line between the effectiveness and safety of reducing blood glucose in the acute phase of MI. The targets must not exceed a reduction greater than 36 mg/dL in relation to estimated average blood glucose.

Cardiovascular risk factors as determinants of retinal and skin microvascular function: The Maastricht Study

Objective

Microvascular dysfunction is an important underlying mechanism of microvascular diseases. Determinants (age, sex, hypertension, dyslipidemia, hyperglycemia, obesity, and smoking) of macrovascular diseases affect large-artery endothelial function. These risk factors also associate with microvascular diseases. We hypothesized that they are also determinants of microvascular (endothelial) function.

Methods

In The Maastricht Study, a type 2 diabetes-enriched population-based cohort study (n = 1991, 51% men, aged 59.7±8.2 years), we determined microvascular function as flicker light-induced retinal arteriolar %-dilation and heat-induced skin %-hyperemia. Multiple linear regression analyses were used to assess the associations of cardiovascular risk factors (age, sex, waist circumference, total-to-high-density lipoprotein (HDL) cholesterol ratio, fasting plasma glucose (FPG), 24-h systolic blood pressure, and cigarette smoking) with retinal and skin microvascular function.

Results

In multivariate analyses, age and FPG were inversely associated with retinal and skin microvascular function (regression coefficients per standard deviation (SD) were -0.11SD (95%CI: -0.15;-0.06) and -0.12SD (-0.17;-0.07) for retinal arteriolar %-dilation and -0.10SD (-0.16;-0.05) and -0.11SD (-0.17;-0.06) for skin %-hyperemia, respectively. Men and current smokers had -0.43SD (-0.58;-0.27) and -0.32SD (-0.49;-0.15) lower skin %-hyperemia, respectively. 24-h systolic blood pressure, waist circumference, and total-to-HDL cholesterol ratio were not statistically significantly associated with these microvascular functions.

Conclusions

Associations between cardiovascular risk factors and retinal and skin microvascular function show a pattern that is partly similar to the associations between cardiovascular risk factors and macrovascular function. Impairment of microvascular function may constitute a pathway through which an adverse cardiovascular risk factor pattern may increase risk of diseases that are partly or wholly of microvascular origin.

A Single Session of Neuromuscular Electrical Stimulation Enhances Vascular Endothelial Function and Peripheral Blood Circulation in Patients With Acute Myocardial Infarction

This study aimed to investigate whether a single session of neuromuscular electrical stimulation (NMES) can enhance vascular endothelial function and peripheral blood circulation in patients with acute myocardial infarction (AMI). Thirty-four male patients with AMI were alternately assigned to 2 groups, and received NMES with muscle contraction (NMES group, n = 17) or without muscle contraction (control group, n = 17) after admission. NMES was performed for quadriceps and gastrocnemius muscles of both legs for 30 minutes. We measured systolic blood pressure as a parameter of cardiovascular responses and the low-frequency component of blood pressure variability as an index of sympathetic activity. Reactive hyperemia peripheral arterial tonometry (RH-PAT) index and transcutaneous oxygen pressure in foot (Foot-tcPO₂) were also measured as parameters of vascular endothelial function and peripheral blood circulation, respectively. All patients completed the study without severe adverse events. Systolic blood pressure and the low-frequency component increased significantly during the NMES session in both groups (P < 0.01 and P < 0.05, respectively). However, elevation from systolic blood pressure at rest was < 10 mmHg in both groups. In the NMES group, the RH-PAT index and Foot-tcPO₂ increased significantly after NMES (P < 0.05 and P < 0.001, respectively). No significant changes were observed in these parameters throughout the session in the control group. In conclusion, a single session of NMES with muscle contraction enhanced vascular endothelial function, leading to improvement in peripheral blood circulation without inducing excessive cardiovascular and autonomic responses in patients with AMI (UMIN000014196).

Clinical Profile and Long-Term Prognostic Factors of a Young Chinese Han Population (≤ 40 Years) Having ST-Segment Elevation Myocardial Infarction

BACKGROUND

The proportion of the mainland Chinese population with premature ST-segment elevation myocardial infarction is significantly elevated. Young patients with ST-segment elevation myocardial infarction have a different risk factor profile and clinical outcome compared with elder patients, and may also differ as compared to young patients in Western populations.

METHODS

We analyzed a total of 9462 consecutive ST-segment elevation myocardial infarction patients, and recruited 341 consecutive cases who had survived their first ST-segment elevation myocardial infarction at the age less than 40 years, and followed-up these patients for 5 years.

RESULTS

The most prevalent risk factor in young Chinese ST-segment elevation myocardial infarction patients was smoking (307/341, 90.03%) and male gender (328/341, 96.19%), although young patients had fewer traditional risk factors of acute myocardial infarction than the control group [(1.63 ± 1.03) vs. (2.38 ± 1.15), p < 0.01]. The number of affected vessels in cases was significantly less than in the elder control group (p < 0.01). During the follow-up, blood lipids and blood pressure of most patients reached the target level, while 42.10% of patients reported continuation of smoking. Multivariable data analysis showed that persistence of smoking (OR: 3.784, 95% CI: 1.636-8.751, p < 0.01) was the most significant prognostic factor of cardiac events after adjusting for various confounding factors.

CONCLUSIONS

We demonstrated that cigarette smoking is the most prevalent factor among the avoidable cardiovascular risk factors for young ST-segment elevation myocardial infarctions in China. Accordingly, continued smoking is the most powerful predictor for the recurrence of cardiac events in young Chinese patients with ST-segment elevation myocardial infarction.

KEY WORDS

Premature myocardial infarction; Prognosis; Risk factor.

Endothelial dysfunction evaluated by peripheral arterial tonometry is related with peak TnI values in patients with ST elevation myocardial infarction treated with primary angioplasty

PURPOSE

The role of endothelial-dependent function in patients with acute ST elevation myocardial infarction (STEMI) is not clear. Endothelial dysfunction may contribute to the pathophysiological processes occurring after STEMI and influence the extension of myocardial necrosis. Endothelial-dependent dysfunction evaluated by peripheral arterial tonometry (PAT) has already showed to be correlated with microvascular coronary endothelial dysfunction. Our purpose was to evaluate the impact of endothelial dysfunction on peak Troponin I (TnI) values, as a surrogate for the extension of myocardial infarction, in patients with STEMI treated with primary angioplasty (P-PCI).

METHODS

58 patients with STEMI treated with P-PCI (mean age 59.0 ± 14.0 years, 46 males) were included. Endothelial function was assessed by reactive hyperaemia index (RHI) determined by PAT. Patients were divided in two groups according to the previously reported RHI threshold for high risk (1.67). The extension of myocardial necrosis was evaluated by peak TnI levels.

RESULTS

RHI median value was 1.78 (IQR0.74);25 patients had endothelial dysfunction (RHI b 1.67). The two groups had no significant differences in age, gender, main risk factors and pain-to-balloon time. Patients with an RHI b 1.67 had significant larger infarcts: TnI 73.5 ng/mL (IQR 114.42 ng/mL) versus TnI 33.2 ng/mL (IQR 65.2 ng/mL); p = 0.028. On multivariate analysis, the presence of an RHI b 1.67 kept significant impact on TnI peak values (p=0.02).

CONCLUSIONS

The presence of endothelial-dependent dysfunction, assessed by PAT, is related with higher peak TnI values in STEMI patients treated with P-PCI. These results strength the possibility that endothelial-dependent dysfunction may be a marker of poor prognosis and eventually a therapeutic target in patients with STEMI.

Preventive effects of exenatide on endothelial dysfunction induced by ischemia-reperfusion injury via KATP channels

OBJECTIVE

The purpose of this study was to evaluate whether exenatide administration can prevent impairment in endothelium-dependent vasodilatation induced by ischemia-reperfusion (IR) injury and whether this effect is mediated by K(ATP) channel opening.

METHODS AND RESULTS

In a double-blind, placebo-controlled, crossover design, 20 volunteers were randomly assigned to 2 groups: subcutaneous exenatide (10 μg) or placebo administration. At 30 minutes after the study drug administration, endothelium-dependent flow-mediated dilatation (FMD) of the radial artery was measured before and after IR (15 minutes of ischemia at the level of the brachial artery followed by 15 minutes of reperfusion) injury. Seven days later, both groups were crossed over and received the other treatment (ie, placebo or exenatide) and underwent the same protocol. Pre-IR radial artery diameter, FMD, and baseline radial artery diameter after IR injury were similar between 2 groups (P=no significant difference). After placebo administration, IR significantly blunted FMD (before IR: 12.0±6.23%; after IR: 4.6±3.57%, P=0.02). Exenatide prevented this impairment (FMD before IR: 15.0±7.14%; FMD after IR: 15.0±5.96%, P=no significant difference; P<0.001 compared with placebo). In a separate protocol, this protective effect was completely abolished by pretreatment with glibenclamide (glyburide, 5 mg), a blocker of K(ATP) channels (n=7; FMD before IR: 12.0±2.2%; after IR: 3.2±2.1%, P<0.001).

CONCLUSIONS

The present study demonstrates that subcutaneous exenatide protects IR-induced endothelial dysfunction through opening of K(ATP) channels in human IR injury model.

Prostanoids suppress the coronary vasoconstrictor influence of endothelin after myocardial infarction

Myocardial infarction (MI) is associated with endothelial dysfunction resulting in an imbalance in endothelium-derived vasodilators and vasoconstrictors. We have previously shown that despite increased endothelin (ET) plasma levels, the coronary vasoconstrictor effect of endogenous ET is abolished after MI. In normal swine, nitric oxide (NO) and prostanoids modulate the vasoconstrictor effect of ET. In light of the interaction among NO, prostanoids, and ET combined with endothelial dysfunction present after MI, we investigated this interaction in control of coronary vasomotor tone in the remote noninfarcted myocardium after MI. Studies were performed in chronically instrumented swine (18 normal swine; 13 swine with MI) at rest and during treadmill exercise. Furthermore, endothelial nitric oxide synthase (eNOS) and cyclooxygenase protein levels were measured in the anterior (noninfarcted) wall of six normal and six swine with MI. eNOS inhibition with N(ω)-nitro-L-arginine (L-NNA) and cyclooxygenase inhibition with indomethacin each resulted in coronary vasoconstriction at rest and during exercise, as evidenced by a decrease in coronary venous oxygen levels. The effect of l-NNA was slightly decreased in swine with MI, although eNOS expression was not altered. Conversely, in accordance with the unaltered expression of cyclooxygenase-1 after MI, the effect of indomethacin was similar in normal and MI swine. L-NNA enhanced the vasodilator effect of the ET(A/B) receptor blocker tezosentan but exclusively during exercise in both normal and MI swine. Interestingly, this effect of L-NNA was blunted in MI compared with normal swine. In contrast, whereas indomethacin increased the vasodilator effect of tezosentan only during exercise in normal swine, indomethacin unmasked a coronary vasodilator effect of tezosentan in MI swine both at rest and during exercise. In conclusion, the present study shows that endothelial control of the coronary vasculature is altered in post-MI remodeled myocardium. Thus the overall vasodilator influences of NO as well as its inhibition of the vasoconstrictor influence of ET on the coronary resistance vessels were reduced after MI. In contrast, while the overall prostanoid vasodilator influence was maintained, its inhibition of ET vasoconstrictor influences was enhanced in post-MI remote myocardium.